Many products of commercial value (such as oil- and water-repellent finishes for textiles, paper, electronic articles, and the like; stain-repellent finishes for leather; and surfactants for a variety of applications) can be made from fluorocarboxylic acid halides. Fluorocarboxylic acid fluorides can be prepared from telomers of tetrafluoroethylene followed by appropriate oxidation, but a characteristic of this method is that a distribution of molecular weights is obtained.
Fluorocarboxylic acid fluorides can also be prepared by electrochemical fluorination (ECF) of the corresponding hydrocarbon carboxylic acid (or a derivative thereof), using either anhydrous hydrogen fluoride (Simons ECF) or KF.multidot.2HF (Phillips ECF) as the electrolyte. However, a drawback of Simons ECF is that side reactions often occur, and low purity and low yields (particularly at higher molecular weights) are often obtained due to the formation of rearrangement and degradation products. (See, e.g., the discussion by T. Abe et al. in Preparation, Properties, and Industrial Applications of Organofluorine Compounds, edited by R. E. Banks, John Wiley & Sons, pages 24-28, New York (1982).)
Although Phillips ECF (KF.multidot.2HF) or direct fluorination (F.sub.2) can be employed to reduce the occurrence of side reactions and provide high yields of a desired fluorinated product, higher molecular weight hydrocarbon carboxylic acids cannot be fluorinated by such techniques without undergoing decarboxylation and/or other side reactions. Hydrocarbon carboxylic acid halides are extremely water-sensitive and difficult to handle, and hydrocarbon carboxylic acid chlorides yield chlorine-substituted fluorochemical products.
Thus, improved routes to fluorocarboxylic acid halides are highly desired in the art.